I’m sure this has been covered a lot, but I’m writing it down so I don’t forget how I did it. If it helps anyone else then great.
1. Locate IIS Express in the system tray
2. Select Show All Application in IIS Express, and select your site in the list
3. Click on the link in the Config section
Find your site, duplicate the localhost binding element and replace localhost with the IP Address of your machine;
4. With IIS Express tool stop all sites and then re-run your site. NOTE YOU MUST BE RUNNING as Administrator, only admin can allow IIS Express to bind to a non-localhost address
Your emulators should now be able to access the site using your machine’s IP Address.
I’ve found a much nicer explanation Accessing an IIS Express site from a remote computer